Image display

Abstract

An image display device has a plurality of electrodes that control a beam between a group of linear cathodes ( 2 ) and a screen ( 8 ) with a phosphor layer, and is provided with a circuit ( 31 ) for generating a beam track offset signal, which generates a signal for slightly oscillating one of the beams horizontally, a PIN photodiode ( 33 ) for detecting the emission amount of the phosphor layer for this beam, a comparator ( 35 ) for generating a beam irradiation position misalignment signal based on the detected emission amount, an integrating circuit ( 36 ) for generating a beam position control signal in correspondence with the beam irradiation position misalignment signal; and a horizontal deflection electrode driving circuit ( 39 ) for driving a horizontal deflection electrode ( 6 ) in accordance with the beam position control signal. With this configuration, misalignments of the position of the beam spot and the phosphor stripes on the screen, which are caused for various reasons, can be suppressed, and an image display device is obtained, in which a deterioration of the image quality, such as color misalignments, does not occur.

What is claimed is:  
     
       1. An image display device comprising: 
       an emission source for electron beams;  
       a display screen having a phosphor layer, wherein phosphors are formed in a certain pattern and separated by a black matrix;  
       an electron beam track controlling system, said electron beam track controlling system having the function to selectively irradiate said electron beams onto predetermined positions of said phosphor layer;  
       a system for applying a defined offset to the electron beam track with respect to the phosphor layer at a certain position;  
       a system for detecting an emission amount of said phosphor layer at the certain position generated by said offset electron beam;  
       a system for recognizing a misalignment of said electron beams at an incident position, based on said emission amount;  
       a system for correcting misalignment of said electron beams at the incident position by feedback of said misalignment at the incident position to said electron beam track controlling system.  
     
     
       2. The image display device according to claim  1 , wherein the system for recognizing a misalignment at an incident position of said electron beams compares (i) an emission amount of the phosphor layer at a position that is defined by applying a certain offset to an electron beam track with respect to a center of the phosphor layer at a certain position, with (ii) an emission amount of the phosphor layer at a position that is defined by applying another offset that is opposite to the certain offset of said electron beam track with respect to the center of said phosphor layer. 
     
     
       3. The image display device according to claim  1 , wherein the system for recognizing a misalignment at an incident position of an electron beam compares (i) an emission amount of the phosphor layer at a position that is defined by applying a certain offset to an electron beam track with respect to a center of the phosphor layer at a certain position, with (ii) an appropriate emission amount of the phosphor layer at that position. 
     
     
       4. The image display device according to claim  1 , wherein said system for detecting the emission amount of the phosphor layer uses a PIN photodiode. 
     
     
       5. The image display device according to claim  2 , wherein said system for detecting the emission amount of the phosphor layer uses a PIN photodiode. 
     
     
       6. The image display device according to claim  3 , wherein said system for detecting the emission amount of the phosphor layer uses a PIN photodiode.